"We are going to fall further, continuing the downtrend and I see an all-time low of the dollar index at 70.65," Tostrams said. "So a lot of selling pressure still ahead in the U.S. dollar."

The index is starting to break a vital support level between 74 and 76 points, Tostrams said. A break below this support level would confirm the selloff, he added.

The dollar looks set to lose more ground against the euro because it too is breaking through a key resistance level, Tostrams said. But the yen may not fair as well against the greenback, according to Tostrams.

"The dollar is now gaining strength against the yen," Tostrams said.

"Now that the falling trend lies behind us we could see some buying in the dollar against the yen. First target is at 92.20 (yen per dollar)," he added.